ADAPTER 8B7557 - Caterpillar

Illustration 1 g01185998
Schematic of the Sensor Power SupplyThis diagnostic code is recorded when the main display module reads an above normal sensor supply voltage (+8 DCV).Note: The procedures that are used to troubleshoot this diagnostic code may cause additional diagnostic codes to be logged. Find the cause and repair the cause of this diagnostic code before you troubleshoot any new diagnostic codes.Test Step 1. CHECK THE VOLTAGE AT THE MAIN DISPLAY MODULE.
Use the 7X-1710 Multimeter Probe in order to check the voltage at the connector for the main display module. Measure the voltage from the contact 24 to the contact 2 (ground). DO NOT disconnect the harness from the module.Expected Result:The supply voltage that is measured is 8.0 0.5 DCV.Results:
YES - The voltage is 8.0 0.5 DCV. The sensor supply voltage is correct. Verify that the diagnostic code is still present. If the diagnostic code is still present the main display module has failed.Repair: It is unlikely that the main display module has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code indicator is illuminated for this diagnostic code. If the cause of the diagnostic code is not found, replace the module. See Troubleshooting, "Main Display Module - Replace".STOP
NO - The voltage is NOT 8.0 0.5 DCV. The sensor supply voltage is NOT correct. Proceed to test step 2.Test Step 2. CHECK FOR A SHORT TO +BATTERY
Disconnect the machine harness from the main display module.
At the machine harness connector for the main display module, measure the voltage from the connector contact 24 to 2 (ground).Expected Result:The voltage that is measured should be approximately 0 DCV.Results:
YES - The voltage is approximately 0 DCV. The voltage is correct. Repair: It is unlikely that the main display module has failed. Exit this procedure and perform this procedure again. Also, recheck if the diagnostic code indicator is illuminated for this diagnostic code. If the cause of the diagnostic code is not found, replace the module. SeeTroubleshooting, "Main Display Module - Replace".STOP
NO - The voltage is NOT approximately 0 DCV. The harness or a sensor has failed. Proceed to test step 3.Test Step 3. DISCONNECT THE SENSORS.
Disconnect one of the sensors. The sensors are connected to the sensor power supply +8 DCV of the main display module. Disconnect the sensor from the machine harness.
After you disconnect the sensor, measure the voltage from the connector contact 2 (ground) to contact 24 of the machine harness connector for the main display module.Expected Result:The voltage that is measured should be approximately 0 DCV.Results:
YES - The voltage is approximately 0 DCV. The voltage is correct. The sensor that was just disconnected has failed.Repair: Replace the sensor.STOP
NO - The voltage is NOT approximately 0 DCV. The harness or a sensor has failed. Repeat this test. The machine harness is shorted to the +battery if all the sensors have been disconnected from the machine harness and the voltage is NOT approximately 0 DCV.Repair: Repair the harness or replace the harness.STOP